Project Summary There is no consensus nor strong evidence that identifies the best rehabilitative protocol to optimize outcomes for patients with surgical repair of a lacerated flexor tendon of the hand. Successful functional recovery requires tendon coaptation, unimpeded tendon gliding, and adequate tensile strength of the repaired tendon. Due to limited evidence and variation in practice, adverse healing outcomes (e.g., tendon ruptures, scar adhesions) occur in a significant number of patients; some patients require a secondary surgery which is costly, less effective, and oftentimes preventable. The training and research conducted through this fellowship will support proficiency in three primary areas related to enhancing the recovery process: 1) musculoskeletal sonography, 2) morphological process of tendon healing, and 3) research methods and data analytic techniques. This fellowship will examine morphologic biomarkers of tendon coaptation using sonographic imaging. Sonographic imaging is a relatively inexpensive, widely available, non-invasive, and pain-free imaging modality that provides real-time images of anatomical structures under the skin. Sonography has been used to evaluate healthy and injured tendons, and sonographic measures have been shown to correlate with functional outcomes. However, an approach for utilizing these biomarkers to inform clinical practice has yet to be fully developed or deployed. As such, this project aims to establish a foundation for the application of sonographic imaging to aid and advance the rehabilitation of flexor tendons. As a first step, a standardized, reliable, and valid sonographic imaging protocol to evaluate tendon healing will be developed. Both static and dynamic imaging techniques will be explored to identify various candidate biomarkers, including macro-morphologic measures of tendon gapping and adhesions, as well as micro-morphologic measures using spatial frequency analysis. The timing for initiation and frequency of data collection to adequately capture changes in the healing tendon, along with the most salient sonographic biomarkers that best indicate healing and functional recovery, will be identified. These biomarkers will be used to explore recovery patterns and characterize the process of tendon healing. Establishing a reliable image analysis protocol and identifying the most salient biomarkers will be a critical step to understanding factors that promote tendon healing with safe and efficient recovery. Successfully accomplishing these aims will be instrumental in advancing practice by supporting the development of a precision medicine approach to tendon rehabilitation.